Generating precise local coordinate system for a rigid body

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c.s.chapman
Posts: 4
Joined: Wed May 25, 2011 3:10 pm

Generating precise local coordinate system for a rigid body

Post by c.s.chapman » Wed Mar 16, 2016 8:32 pm

How do I define a precise coordinate system based on the known geometry of 6 markers making up a rigid body? That is, I need to exactly define through / relative to which markers each of the three axes runs. I also need to precisely position the centre relative to the markers (and not in the geometric mean).

It is not good enough to place it in approximately the right orientation relative to the global system and have it inherit that coordinate frame - this needs to be precise and repeatable. I also use a Vicon system and they enable this kind of thing in their Tracker program via .vsk files for each object - does something similar exist for Optitrak?

Any advice would be much appreciated,

Craig Chapman

steven.andrews
NaturalPoint Employee
NaturalPoint Employee
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Joined: Mon Jan 19, 2015 11:52 am

Re: Generating precise local coordinate system for a rigid b

Post by steven.andrews » Thu Mar 17, 2016 11:14 am

Hello Craig,

Thank you for using OptiTrack and thank you for reaching out to us regarding your questions.

There are tools available that allow you to adjust the position and orientation of the rigid body's pivot point.

I would suggest a workflow in which you snap the pivot point to a marker that is carefully placed near the desired location. You can then apply translation and rotation offsets to set the rigid body exactly as you need it to track. You can find the steps for this workflow on our wiki.
http://wiki.optitrack.com/index.php?tit ... ivot_Point

Once you have set your rigid body exactly as you need it, you can right-click the rigid body in the Project panel to export it. You can reload the rigid body file in future sessions to track the object in a consistent way.

I hope you find this information to be useful. If you require any further assistance, please feel free to reach out to us through help.naturalpoint.com

Best regards,
Steven
--
Steven Andrews
OptiTrack | Customer Support Engineer

dlgaudet
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Joined: Tue Mar 29, 2016 11:13 am

Re: Generating precise local coordinate system for a rigid b

Post by dlgaudet » Tue Mar 29, 2016 11:20 am

I would like to do the same thing, namely, provide engineering data of the target locations with the desired local co-ordinate system on various rigid bodies. The above methodology, while we can muddle through with it, is not desirable and is prone to adding in mistakes. The ability to upload a rigid body definition with ball locations, pivot point, and the local co-ordinate system defined would be greatly appreciated.

With the method you propose, we will need to re-check everything as compared to our engineering data at the end, after running through this convoluted procedure.

steven.andrews
NaturalPoint Employee
NaturalPoint Employee
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Joined: Mon Jan 19, 2015 11:52 am

Re: Generating precise local coordinate system for a rigid b

Post by steven.andrews » Wed Mar 30, 2016 1:10 pm

Hello dlgaudet,

Rigid Body editing is something that we are looking to improve, so we hope to provide better tools for this in the next couple of versions. Better tools for calculating and placing the Rigid Body's pivot point may help to address difficulties in this setup.

I will put in a feature request for readable and editable Rigid Body files as well.

Cheers,
Steven
--
Steven Andrews
OptiTrack | Senior Customer Support Engineer

matthew
Posts: 10
Joined: Fri Sep 08, 2017 3:47 pm

Re: Generating precise local coordinate system for a rigid b

Post by matthew » Fri Sep 08, 2017 4:39 pm

Has there been any progress on this, or is your suggested workflow still to manually tweak the offsets in the GUI until it "looks right"?

It seems pretty dishonest to market your product as a precision engineering tool when you don't even have the basic features we expect from Vicon (editable rigid bodies and "snap rotation to marker").

steven.andrews
NaturalPoint Employee
NaturalPoint Employee
Posts: 571
Joined: Mon Jan 19, 2015 11:52 am

Re: Generating precise local coordinate system for a rigid b

Post by steven.andrews » Mon Sep 11, 2017 12:32 pm

Hello matthew,

Thank you for checking on this. We have made several improvements to the rigid body editing tools, which will allow you to use marker data to define targets when changing the position and orientation of the pivot point.

These new features are available in the new Motive 2.0 Beta. Documentation for the features can be found here.

Best,
Steven
--
Steven Andrews
OptiTrack | Senior Customer Support Engineer
help.naturalpoint.com
support@optitrack.com

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